1. Field of the Invention
The present invention relates generally to a process for preparing a long chain alkyl quaternary ammonium salt powder. More particularly, the invention relates to a process for preparing a long chain alkyl quaternary ammonium salt powder by spray-cooling.
2. Description of the Prior Art
Long chain alkyl quaternary ammonium salts have been used broadly as sterilizers, softening agents for fibers or bases of rinsing agents. Those quaternary ammonium salt products are in many cases in the form of solutions. On the other hand, however, the ammonium salts in the form of powders are required in many cases according to their use or from an economical viewpoint. In such cases, the powders have been obtained by recrystallization or pulverization of blocks. However, those processes require a great amount of labor and a large apparatus and the workability thereof is very poor, since, for example, dusts are formed. Further, the particles thus obtained have irregular, uneven particle sizes and, therefore, a sieving or screening operation is required in many cases.
Generally, as a process for obtaining such powdery products, there may be mentioned, in addition to said reprecipitation process and pulverization process, a granulation process by means of spray-cooling. This process comprises dispersing a molten liquid at a temperature above its melting point through a nozzle and thereby contacting the same with cooled air to obtain the powder. Thus, it has been considered that said process is advantageous, since the operations of lump-preparation, pulverization and sieving are unnecessary and a high efficiency is obtained. In fact, numerous chemical products have been pulverized by the spray-cooling granulation process on a commercial scale.
However, the application of the spray-cooling granulation process to long chain quaternary ammonium salts has been impossible, since the salts do not have a satisfactory fluidity or stability at high temperatures.